The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
High-speed watercraft rely on hydrodynamic forces to elevate the hull above its at rest position. The at rest position is known as the displacement depth. When the hull is elevated above its normal position, the watercraft is said to be planing. While planing, the watercraft is subjected to severe forces resulting from the impact of the watercraft with waves. The body or hull may subject the hull to potential damage. Also, the forces may create vibrations and also cause the propeller or rutter to lose optimal immersion in the water. Because of these forces, a reduction in speed may be required to change direction of travel. Slowing during a race in high speed watercraft is not desirable. Hydroplanes are one example of an extreme use of planing to minimize hull drag.
Referring now to FIG. 1, major features of a watercraft 10, such as a hydroplane, are illustrated. The watercraft 10 includes an engine 12 mounted to a hull 14. The engine 12 drives a propeller 16. The hull 14 includes a cockpit 18. Sponsons 20, 21 are rigidly attached to the fore portion of the hull 14. The driver sits in the cockpit 18 and controls the speed of the engine and a rudder (not shown). An adjustable wing or canard 24 is mounted between the sponsons 20, 21 and is also controlled by the driver within the cockpit 18. The canard 24 may be adjusted to produce a desired aerodynamic force to maintain stability. A foot pedal within the cockpit 18 is typically used to adjust the canard 24. An air intake 28 is used for providing air into the engine 12.
Referring now to FIG. 2, by adjusting the canard 24, the air trap 30 between the bottom of the hull and the surface of the water is increased or decreased which, in turn, increases or decreases the clearance 32.
Referring now to FIG. 3, at speed, the watercraft 10 typically touches the water in three locations. Each sponson 20, 21 touch the water at a contact area 40. The third location is the propeller 16. A desired contact position for the propeller 16 is about halfway across the propeller 16. The pressure increase within the air trap causes hydrodynamic lift that causes the hull 14 to establish the running clearance 32. The canard 24, illustrated in FIGS. 1 and 2, is adjusted to keep the clearance 32 at a desired value to counteract the impact of the waves on the sponsons 20, 21. Wind gusts, however, may affect the pressure within the air trap 30.
The propeller 16 provides a horizontal thrust force to propel the craft forward and also provides a vertical thrust force to lift the aft portion of the hull clear of the water. Propeller efficiency is reduced when a deviation from ideal immersion is present.
Referring now to FIG. 4, the watercraft 10 is illustrated in an elevated position that shows the motion of air 50 that results in placing the craft in an out-of-control condition during a flip or roll. At high speeds, relatively small waves may result in a strong vertical force acting on the sponsons that allow the motion of air 50 to lift the watercraft and move the watercraft in an up and outward direction.